text: //========================================================================
  // GLFW 3.4 WGL - www.glfw.org
  //------------------------------------------------------------------------
  // Copyright (c) 2002-2006 Marcus Geelnard
  // Copyright (c) 2006-2019 Camilla Löwy <elmindreda@glfw.org>
  //
  // This software is provided 'as-is', without any express or implied
  // warranty. In no event will the authors be held liable for any damages
  // arising from the use of this software.
  //
  // Permission is granted to anyone to use this software for any purpose,
  // including commercial applications, and to alter it and redistribute it
  // freely, subject to the following restrictions:
  //
  // 1. The origin of this software must not be misrepresented; you must not
  //    claim that you wrote the original software. If you use this software
  //    in a product, an acknowledgment in the product documentation would
  //    be appreciated but is not required.
  //
  // 2. Altered source versions must be plainly marked as such, and must not
  //    be misrepresented as being the original software.
  //
  // 3. This notice may not be removed or altered from any source
  //    distribution.
  //
  //========================================================================
  // Please use C89 style variable declarations in this file because VS 2010
  //========================================================================
  
  #include "internal.h"
  
  #include <stdlib.h>
  #include <assert.h>
  
  // Return the value corresponding to the specified attribute
  //
  static int findPixelFormatAttribValueWGL(const int* attribs,
                                           int attribCount,
                                           const int* values,
                                           int attrib)
  {
      int i;
  
      for (i = 0;  i < attribCount;  i++)
      {
          if (attribs[i] == attrib)
              return values[i];
      }
  
      _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                           "WGL: Unknown pixel format attribute requested");
      return 0;
  }
  
  #define ADD_ATTRIB(a) \
  { \
      assert((size_t) attribCount < sizeof(attribs) / sizeof(attribs[0])); \
      attribs[attribCount++] = a; \
  }
  #define FIND_ATTRIB_VALUE(a) \
      findPixelFormatAttribValueWGL(attribs, attribCount, values, a)
  
  // Return a list of available and usable framebuffer configs
  //
  static int choosePixelFormatWGL(_GLFWwindow* window,
                                  const _GLFWctxconfig* ctxconfig,
                                  const _GLFWfbconfig* fbconfig)
  {
      _GLFWfbconfig* usableConfigs;
      const _GLFWfbconfig* closest;
      int i, pixelFormat, nativeCount, usableCount = 0, attribCount = 0;
      int attribs[40];
      int values[sizeof(attribs) / sizeof(attribs[0])];
  
      if (_glfw.wgl.ARB_pixel_format)
      {
          const int attrib = WGL_NUMBER_PIXEL_FORMATS_ARB;
  
          if (!wglGetPixelFormatAttribivARB(window->context.wgl.dc,
                                            1, 0, 1, &attrib, &nativeCount))
          {
              _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                                   "WGL: Failed to retrieve pixel format attribute");
              return 0;
          }
  
          ADD_ATTRIB(WGL_SUPPORT_OPENGL_ARB);
          ADD_ATTRIB(WGL_DRAW_TO_WINDOW_ARB);
          ADD_ATTRIB(WGL_PIXEL_TYPE_ARB);
          ADD_ATTRIB(WGL_ACCELERATION_ARB);
          ADD_ATTRIB(WGL_RED_BITS_ARB);
          ADD_ATTRIB(WGL_RED_SHIFT_ARB);
          ADD_ATTRIB(WGL_GREEN_BITS_ARB);
          ADD_ATTRIB(WGL_GREEN_SHIFT_ARB);
          ADD_ATTRIB(WGL_BLUE_BITS_ARB);
          ADD_ATTRIB(WGL_BLUE_SHIFT_ARB);
          ADD_ATTRIB(WGL_ALPHA_BITS_ARB);
          ADD_ATTRIB(WGL_ALPHA_SHIFT_ARB);
          ADD_ATTRIB(WGL_DEPTH_BITS_ARB);
          ADD_ATTRIB(WGL_STENCIL_BITS_ARB);
          ADD_ATTRIB(WGL_ACCUM_BITS_ARB);
          ADD_ATTRIB(WGL_ACCUM_RED_BITS_ARB);
          ADD_ATTRIB(WGL_ACCUM_GREEN_BITS_ARB);
          ADD_ATTRIB(WGL_ACCUM_BLUE_BITS_ARB);
          ADD_ATTRIB(WGL_ACCUM_ALPHA_BITS_ARB);
          ADD_ATTRIB(WGL_AUX_BUFFERS_ARB);
          ADD_ATTRIB(WGL_STEREO_ARB);
          ADD_ATTRIB(WGL_DOUBLE_BUFFER_ARB);
  
          if (_glfw.wgl.ARB_multisample)
              ADD_ATTRIB(WGL_SAMPLES_ARB);
  
          if (ctxconfig->client == GLFW_OPENGL_API)
          {
              if (_glfw.wgl.ARB_framebuffer_sRGB || _glfw.wgl.EXT_framebuffer_sRGB)
                  ADD_ATTRIB(WGL_FRAMEBUFFER_SRGB_CAPABLE_ARB);
          }
          else
          {
              if (_glfw.wgl.EXT_colorspace)
                  ADD_ATTRIB(WGL_COLORSPACE_EXT);
          }
      }
      else
      {
          nativeCount = DescribePixelFormat(window->context.wgl.dc,
                                            1,
                                            sizeof(PIXELFORMATDESCRIPTOR),
                                            NULL);
      }
  
      usableConfigs = _glfw_calloc(nativeCount, sizeof(_GLFWfbconfig));
  
      for (i = 0;  i < nativeCount;  i++)
      {
          _GLFWfbconfig* u = usableConfigs + usableCount;
          pixelFormat = i + 1;
  
          if (_glfw.wgl.ARB_pixel_format)
          {
              // Get pixel format attributes through "modern" extension
  
              if (!wglGetPixelFormatAttribivARB(window->context.wgl.dc,
                                                pixelFormat, 0,
                                                attribCount,
                                                attribs, values))
              {
                  _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                                      "WGL: Failed to retrieve pixel format attributes");
  
                  _glfw_free(usableConfigs);
                  return 0;
              }
  
              if (!FIND_ATTRIB_VALUE(WGL_SUPPORT_OPENGL_ARB) ||
                  !FIND_ATTRIB_VALUE(WGL_DRAW_TO_WINDOW_ARB))
              {
                  continue;
              }
  
              if (FIND_ATTRIB_VALUE(WGL_PIXEL_TYPE_ARB) != WGL_TYPE_RGBA_ARB)
                  continue;
  
              if (FIND_ATTRIB_VALUE(WGL_ACCELERATION_ARB) == WGL_NO_ACCELERATION_ARB)
                  continue;
  
              if (FIND_ATTRIB_VALUE(WGL_DOUBLE_BUFFER_ARB) != fbconfig->doublebuffer)
                  continue;
  
              u->redBits = FIND_ATTRIB_VALUE(WGL_RED_BITS_ARB);
              u->greenBits = FIND_ATTRIB_VALUE(WGL_GREEN_BITS_ARB);
              u->blueBits = FIND_ATTRIB_VALUE(WGL_BLUE_BITS_ARB);
              u->alphaBits = FIND_ATTRIB_VALUE(WGL_ALPHA_BITS_ARB);
  
              u->depthBits = FIND_ATTRIB_VALUE(WGL_DEPTH_BITS_ARB);
              u->stencilBits = FIND_ATTRIB_VALUE(WGL_STENCIL_BITS_ARB);
  
              u->accumRedBits = FIND_ATTRIB_VALUE(WGL_ACCUM_RED_BITS_ARB);
              u->accumGreenBits = FIND_ATTRIB_VALUE(WGL_ACCUM_GREEN_BITS_ARB);
              u->accumBlueBits = FIND_ATTRIB_VALUE(WGL_ACCUM_BLUE_BITS_ARB);
              u->accumAlphaBits = FIND_ATTRIB_VALUE(WGL_ACCUM_ALPHA_BITS_ARB);
  
              u->auxBuffers = FIND_ATTRIB_VALUE(WGL_AUX_BUFFERS_ARB);
  
              if (FIND_ATTRIB_VALUE(WGL_STEREO_ARB))
                  u->stereo = GLFW_TRUE;
  
              if (_glfw.wgl.ARB_multisample)
                  u->samples = FIND_ATTRIB_VALUE(WGL_SAMPLES_ARB);
  
              if (ctxconfig->client == GLFW_OPENGL_API)
              {
                  if (_glfw.wgl.ARB_framebuffer_sRGB ||
                      _glfw.wgl.EXT_framebuffer_sRGB)
                  {
                      if (FIND_ATTRIB_VALUE(WGL_FRAMEBUFFER_SRGB_CAPABLE_ARB))
                          u->sRGB = GLFW_TRUE;
                  }
              }
              else
              {
                  if (_glfw.wgl.EXT_colorspace)
                  {
                      if (FIND_ATTRIB_VALUE(WGL_COLORSPACE_EXT) == WGL_COLORSPACE_SRGB_EXT)
                          u->sRGB = GLFW_TRUE;
                  }
              }
          }
          else
          {
              // Get pixel format attributes through legacy PFDs
  
              PIXELFORMATDESCRIPTOR pfd;
  
              if (!DescribePixelFormat(window->context.wgl.dc,
                                       pixelFormat,
                                       sizeof(PIXELFORMATDESCRIPTOR),
                                       &pfd))
              {
                  _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                                      "WGL: Failed to describe pixel format");
  
                  _glfw_free(usableConfigs);
                  return 0;
              }
  
              if (!(pfd.dwFlags & PFD_DRAW_TO_WINDOW) ||
                  !(pfd.dwFlags & PFD_SUPPORT_OPENGL))
              {
                  continue;
              }
  
              if (!(pfd.dwFlags & PFD_GENERIC_ACCELERATED) &&
                  (pfd.dwFlags & PFD_GENERIC_FORMAT))
              {
                  continue;
              }
  
              if (pfd.iPixelType != PFD_TYPE_RGBA)
                  continue;
  
              if (!!(pfd.dwFlags & PFD_DOUBLEBUFFER) != fbconfig->doublebuffer)
                  continue;
  
              u->redBits = pfd.cRedBits;
              u->greenBits = pfd.cGreenBits;
              u->blueBits = pfd.cBlueBits;
              u->alphaBits = pfd.cAlphaBits;
  
              u->depthBits = pfd.cDepthBits;
              u->stencilBits = pfd.cStencilBits;
  
              u->accumRedBits = pfd.cAccumRedBits;
              u->accumGreenBits = pfd.cAccumGreenBits;
              u->accumBlueBits = pfd.cAccumBlueBits;
              u->accumAlphaBits = pfd.cAccumAlphaBits;
  
              u->auxBuffers = pfd.cAuxBuffers;
  
              if (pfd.dwFlags & PFD_STEREO)
                  u->stereo = GLFW_TRUE;
          }
  
          u->handle = pixelFormat;
          usableCount++;
      }
  
      if (!usableCount)
      {
          _glfwInputError(GLFW_API_UNAVAILABLE,
                          "WGL: The driver does not appear to support OpenGL");
  
          _glfw_free(usableConfigs);
          return 0;
      }
  
      closest = _glfwChooseFBConfig(fbconfig, usableConfigs, usableCount);
      if (!closest)
      {
          _glfwInputError(GLFW_FORMAT_UNAVAILABLE,
                          "WGL: Failed to find a suitable pixel format");
  
          _glfw_free(usableConfigs);
          return 0;
      }
  
      pixelFormat = (int) closest->handle;
      _glfw_free(usableConfigs);
  
      return pixelFormat;
  }
  
  #undef ADD_ATTRIB
  #undef FIND_ATTRIB_VALUE
  
  static void makeContextCurrentWGL(_GLFWwindow* window)
  {
      if (window)
      {
          if (wglMakeCurrent(window->context.wgl.dc, window->context.wgl.handle))
              _glfwPlatformSetTls(&_glfw.contextSlot, window);
          else
          {
              _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                                   "WGL: Failed to make context current");
              _glfwPlatformSetTls(&_glfw.contextSlot, NULL);
          }
      }
      else
      {
          if (!wglMakeCurrent(NULL, NULL))
          {
              _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                                   "WGL: Failed to clear current context");
          }
  
          _glfwPlatformSetTls(&_glfw.contextSlot, NULL);
      }
  }
  
  static void swapBuffersWGL(_GLFWwindow* window)
  {
      if (!window->monitor)
      {
          // HACK: Use DwmFlush when desktop composition is enabled on Windows Vista and 7
          if (!IsWindows8OrGreater() && IsWindowsVistaOrGreater())
          {
              BOOL enabled = FALSE;
  
              if (SUCCEEDED(DwmIsCompositionEnabled(&enabled)) && enabled)
              {
                  int count = abs(window->context.wgl.interval);
                  while (count--)
                      DwmFlush();
              }
          }
      }
  
      SwapBuffers(window->context.wgl.dc);
  }
  
  static void swapIntervalWGL(int interval)
  {
      _GLFWwindow* window = _glfwPlatformGetTls(&_glfw.contextSlot);
  
      window->context.wgl.interval = interval;
  
      if (!window->monitor)
      {
          // HACK: Disable WGL swap interval when desktop composition is enabled on Windows
          //       Vista and 7 to avoid interfering with DWM vsync
          if (!IsWindows8OrGreater() && IsWindowsVistaOrGreater())
          {
              BOOL enabled = FALSE;
  
              if (SUCCEEDED(DwmIsCompositionEnabled(&enabled)) && enabled)
                  interval = 0;
          }
      }
  
      if (_glfw.wgl.EXT_swap_control)
          wglSwapIntervalEXT(interval);
  }
  
  static int extensionSupportedWGL(const char* extension)
  {
      const char* extensions = NULL;
  
      if (_glfw.wgl.GetExtensionsStringARB)
          extensions = wglGetExtensionsStringARB(wglGetCurrentDC());
      else if (_glfw.wgl.GetExtensionsStringEXT)
          extensions = wglGetExtensionsStringEXT();
  
      if (!extensions)
          return GLFW_FALSE;
  
      return _glfwStringInExtensionString(extension, extensions);
  }
  
  static GLFWglproc getProcAddressWGL(const char* procname)
  {
      const GLFWglproc proc = (GLFWglproc) wglGetProcAddress(procname);
      if (proc)
          return proc;
  
      return (GLFWglproc) _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, procname);
  }
  
  static void destroyContextWGL(_GLFWwindow* window)
  {
      if (window->context.wgl.handle)
      {
          wglDeleteContext(window->context.wgl.handle);
          window->context.wgl.handle = NULL;
      }
  }
  
  // Initialize WGL
  //
  GLFWbool _glfwInitWGL(void)
  {
      PIXELFORMATDESCRIPTOR pfd;
      HGLRC prc, rc;
      HDC pdc, dc;
  
      if (_glfw.wgl.instance)
          return GLFW_TRUE;
  
      _glfw.wgl.instance = _glfwPlatformLoadModule("opengl32.dll");
      if (!_glfw.wgl.instance)
      {
          _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                               "WGL: Failed to load opengl32.dll");
          return GLFW_FALSE;
      }
  
      _glfw.wgl.CreateContext = (PFN_wglCreateContext)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglCreateContext");
      _glfw.wgl.DeleteContext = (PFN_wglDeleteContext)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglDeleteContext");
      _glfw.wgl.GetProcAddress = (PFN_wglGetProcAddress)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglGetProcAddress");
      _glfw.wgl.GetCurrentDC = (PFN_wglGetCurrentDC)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglGetCurrentDC");
      _glfw.wgl.GetCurrentContext = (PFN_wglGetCurrentContext)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglGetCurrentContext");
      _glfw.wgl.MakeCurrent = (PFN_wglMakeCurrent)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglMakeCurrent");
      _glfw.wgl.ShareLists = (PFN_wglShareLists)
          _glfwPlatformGetModuleSymbol(_glfw.wgl.instance, "wglShareLists");
  
      // NOTE: A dummy context has to be created for opengl32.dll to load the
      //       OpenGL ICD, from which we can then query WGL extensions
      // NOTE: This code will accept the Microsoft GDI ICD; accelerated context
      //       creation failure occurs during manual pixel format enumeration
  
      dc = GetDC(_glfw.win32.helperWindowHandle);
  
      ZeroMemory(&pfd, sizeof(pfd));
      pfd.nSize = sizeof(pfd);
      pfd.nVersion = 1;
      pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
      pfd.iPixelType = PFD_TYPE_RGBA;
      pfd.cColorBits = 24;
  
      if (!SetPixelFormat(dc, ChoosePixelFormat(dc, &pfd), &pfd))
      {
          _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                               "WGL: Failed to set pixel format for dummy context");
          return GLFW_FALSE;
      }
  
      rc = wglCreateContext(dc);
      if (!rc)
      {
          _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                               "WGL: Failed to create dummy context");
          return GLFW_FALSE;
      }
  
      pdc = wglGetCurrentDC();
      prc = wglGetCurrentContext();
  
      if (!wglMakeCurrent(dc, rc))
      {
          _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                               "WGL: Failed to make dummy context current");
          wglMakeCurrent(pdc, prc);
          wglDeleteContext(rc);
          return GLFW_FALSE;
      }
  
      // NOTE: Functions must be loaded first as they're needed to retrieve the
      //       extension string that tells us whether the functions are supported
      _glfw.wgl.GetExtensionsStringEXT = (PFNWGLGETEXTENSIONSSTRINGEXTPROC)
          wglGetProcAddress("wglGetExtensionsStringEXT");
      _glfw.wgl.GetExtensionsStringARB = (PFNWGLGETEXTENSIONSSTRINGARBPROC)
          wglGetProcAddress("wglGetExtensionsStringARB");
      _glfw.wgl.CreateContextAttribsARB = (PFNWGLCREATECONTEXTATTRIBSARBPROC)
          wglGetProcAddress("wglCreateContextAttribsARB");
      _glfw.wgl.SwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)
          wglGetProcAddress("wglSwapIntervalEXT");
      _glfw.wgl.GetPixelFormatAttribivARB = (PFNWGLGETPIXELFORMATATTRIBIVARBPROC)
          wglGetProcAddress("wglGetPixelFormatAttribivARB");
  
      // NOTE: WGL_ARB_extensions_string and WGL_EXT_extensions_string are not
      //       checked below as we are already using them
      _glfw.wgl.ARB_multisample =
          extensionSupportedWGL("WGL_ARB_multisample");
      _glfw.wgl.ARB_framebuffer_sRGB =
          extensionSupportedWGL("WGL_ARB_framebuffer_sRGB");
      _glfw.wgl.EXT_framebuffer_sRGB =
          extensionSupportedWGL("WGL_EXT_framebuffer_sRGB");
      _glfw.wgl.ARB_create_context =
          extensionSupportedWGL("WGL_ARB_create_context");
      _glfw.wgl.ARB_create_context_profile =
          extensionSupportedWGL("WGL_ARB_create_context_profile");
      _glfw.wgl.EXT_create_context_es2_profile =
          extensionSupportedWGL("WGL_EXT_create_context_es2_profile");
      _glfw.wgl.ARB_create_context_robustness =
          extensionSupportedWGL("WGL_ARB_create_context_robustness");
      _glfw.wgl.ARB_create_context_no_error =
          extensionSupportedWGL("WGL_ARB_create_context_no_error");
      _glfw.wgl.EXT_swap_control =
          extensionSupportedWGL("WGL_EXT_swap_control");
      _glfw.wgl.EXT_colorspace =
          extensionSupportedWGL("WGL_EXT_colorspace");
      _glfw.wgl.ARB_pixel_format =
          extensionSupportedWGL("WGL_ARB_pixel_format");
      _glfw.wgl.ARB_context_flush_control =
          extensionSupportedWGL("WGL_ARB_context_flush_control");
  
      wglMakeCurrent(pdc, prc);
      wglDeleteContext(rc);
      return GLFW_TRUE;
  }
  
  // Terminate WGL
  //
  void _glfwTerminateWGL(void)
  {
      if (_glfw.wgl.instance)
          _glfwPlatformFreeModule(_glfw.wgl.instance);
  }
  
  #define SET_ATTRIB(a, v) \
  { \
      assert(((size_t) index + 1) < sizeof(attribs) / sizeof(attribs[0])); \
      attribs[index++] = a; \
      attribs[index++] = v; \
  }
  
  // Create the OpenGL or OpenGL ES context
  //
  GLFWbool _glfwCreateContextWGL(_GLFWwindow* window,
                                 const _GLFWctxconfig* ctxconfig,
                                 const _GLFWfbconfig* fbconfig)
  {
      int attribs[40];
      int pixelFormat;
      PIXELFORMATDESCRIPTOR pfd;
      HGLRC share = NULL;
  
      if (ctxconfig->share)
          share = ctxconfig->share->context.wgl.handle;
  
      window->context.wgl.dc = GetDC(window->win32.handle);
      if (!window->context.wgl.dc)
      {
          _glfwInputError(GLFW_PLATFORM_ERROR,
                          "WGL: Failed to retrieve DC for window");
          return GLFW_FALSE;
      }
  
      pixelFormat = choosePixelFormatWGL(window, ctxconfig, fbconfig);
      if (!pixelFormat)
          return GLFW_FALSE;
  
      if (!DescribePixelFormat(window->context.wgl.dc,
                               pixelFormat, sizeof(pfd), &pfd))
      {
          _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                               "WGL: Failed to retrieve PFD for selected pixel format");
          return GLFW_FALSE;
      }
  
      if (!SetPixelFormat(window->context.wgl.dc, pixelFormat, &pfd))
      {
          _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                               "WGL: Failed to set selected pixel format");
          return GLFW_FALSE;
      }
  
      if (ctxconfig->client == GLFW_OPENGL_API)
      {
          if (ctxconfig->forward)
          {
              if (!_glfw.wgl.ARB_create_context)
              {
                  _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                  "WGL: A forward compatible OpenGL context requested but WGL_ARB_create_context is unavailable");
                  return GLFW_FALSE;
              }
          }
  
          if (ctxconfig->profile)
          {
              if (!_glfw.wgl.ARB_create_context_profile)
              {
                  _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                  "WGL: OpenGL profile requested but WGL_ARB_create_context_profile is unavailable");
                  return GLFW_FALSE;
              }
          }
      }
      else
      {
          if (!_glfw.wgl.ARB_create_context ||
              !_glfw.wgl.ARB_create_context_profile ||
              !_glfw.wgl.EXT_create_context_es2_profile)
          {
              _glfwInputError(GLFW_API_UNAVAILABLE,
                              "WGL: OpenGL ES requested but WGL_ARB_create_context_es2_profile is unavailable");
              return GLFW_FALSE;
          }
      }
  
      if (_glfw.wgl.ARB_create_context)
      {
          int index = 0, mask = 0, flags = 0;
  
          if (ctxconfig->client == GLFW_OPENGL_API)
          {
              if (ctxconfig->forward)
                  flags |= WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
  
              if (ctxconfig->profile == GLFW_OPENGL_CORE_PROFILE)
                  mask |= WGL_CONTEXT_CORE_PROFILE_BIT_ARB;
              else if (ctxconfig->profile == GLFW_OPENGL_COMPAT_PROFILE)
                  mask |= WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB;
          }
          else
              mask |= WGL_CONTEXT_ES2_PROFILE_BIT_EXT;
  
          if (ctxconfig->debug)
              flags |= WGL_CONTEXT_DEBUG_BIT_ARB;
  
          if (ctxconfig->robustness)
          {
              if (_glfw.wgl.ARB_create_context_robustness)
              {
                  if (ctxconfig->robustness == GLFW_NO_RESET_NOTIFICATION)
                  {
                      SET_ATTRIB(WGL_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB,
                                 WGL_NO_RESET_NOTIFICATION_ARB);
                  }
                  else if (ctxconfig->robustness == GLFW_LOSE_CONTEXT_ON_RESET)
                  {
                      SET_ATTRIB(WGL_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB,
                                 WGL_LOSE_CONTEXT_ON_RESET_ARB);
                  }
  
                  flags |= WGL_CONTEXT_ROBUST_ACCESS_BIT_ARB;
              }
          }
  
          if (ctxconfig->release)
          {
              if (_glfw.wgl.ARB_context_flush_control)
              {
                  if (ctxconfig->release == GLFW_RELEASE_BEHAVIOR_NONE)
                  {
                      SET_ATTRIB(WGL_CONTEXT_RELEASE_BEHAVIOR_ARB,
                                 WGL_CONTEXT_RELEASE_BEHAVIOR_NONE_ARB);
                  }
                  else if (ctxconfig->release == GLFW_RELEASE_BEHAVIOR_FLUSH)
                  {
                      SET_ATTRIB(WGL_CONTEXT_RELEASE_BEHAVIOR_ARB,
                                 WGL_CONTEXT_RELEASE_BEHAVIOR_FLUSH_ARB);
                  }
              }
          }
  
          if (ctxconfig->noerror)
          {
              if (_glfw.wgl.ARB_create_context_no_error)
                  SET_ATTRIB(WGL_CONTEXT_OPENGL_NO_ERROR_ARB, GLFW_TRUE);
          }
  
          // NOTE: Only request an explicitly versioned context when necessary, as
          //       explicitly requesting version 1.0 does not always return the
          //       highest version supported by the driver
          if (ctxconfig->major != 1 || ctxconfig->minor != 0)
          {
              SET_ATTRIB(WGL_CONTEXT_MAJOR_VERSION_ARB, ctxconfig->major);
              SET_ATTRIB(WGL_CONTEXT_MINOR_VERSION_ARB, ctxconfig->minor);
          }
  
          if (flags)
              SET_ATTRIB(WGL_CONTEXT_FLAGS_ARB, flags);
  
          if (mask)
              SET_ATTRIB(WGL_CONTEXT_PROFILE_MASK_ARB, mask);
  
          SET_ATTRIB(0, 0);
  
          window->context.wgl.handle =
              wglCreateContextAttribsARB(window->context.wgl.dc, share, attribs);
          if (!window->context.wgl.handle)
          {
              const DWORD error = GetLastError();
  
              if (error == (0xc0070000 | ERROR_INVALID_VERSION_ARB))
              {
                  if (ctxconfig->client == GLFW_OPENGL_API)
                  {
                      _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                      "WGL: Driver does not support OpenGL version %i.%i",
                                      ctxconfig->major,
                                      ctxconfig->minor);
                  }
                  else
                  {
                      _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                      "WGL: Driver does not support OpenGL ES version %i.%i",
                                      ctxconfig->major,
                                      ctxconfig->minor);
                  }
              }
              else if (error == (0xc0070000 | ERROR_INVALID_PROFILE_ARB))
              {
                  _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                  "WGL: Driver does not support the requested OpenGL profile");
              }
              else if (error == (0xc0070000 | ERROR_INCOMPATIBLE_DEVICE_CONTEXTS_ARB))
              {
                  _glfwInputError(GLFW_INVALID_VALUE,
                                  "WGL: The share context is not compatible with the requested context");
              }
              else
              {
                  if (ctxconfig->client == GLFW_OPENGL_API)
                  {
                      _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                      "WGL: Failed to create OpenGL context");
                  }
                  else
                  {
                      _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                                      "WGL: Failed to create OpenGL ES context");
                  }
              }
  
              return GLFW_FALSE;
          }
      }
      else
      {
          window->context.wgl.handle = wglCreateContext(window->context.wgl.dc);
          if (!window->context.wgl.handle)
          {
              _glfwInputErrorWin32(GLFW_VERSION_UNAVAILABLE,
                                   "WGL: Failed to create OpenGL context");
              return GLFW_FALSE;
          }
  
          if (share)
          {
              if (!wglShareLists(share, window->context.wgl.handle))
              {
                  _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
                                       "WGL: Failed to enable sharing with specified OpenGL context");
                  return GLFW_FALSE;
              }
          }
      }
  
      window->context.makeCurrent = makeContextCurrentWGL;
      window->context.swapBuffers = swapBuffersWGL;
      window->context.swapInterval = swapIntervalWGL;
      window->context.extensionSupported = extensionSupportedWGL;
      window->context.getProcAddress = getProcAddressWGL;
      window->context.destroy = destroyContextWGL;
  
      return GLFW_TRUE;
  }
  
  #undef SET_ATTRIB
  
  GLFWAPI HGLRC glfwGetWGLContext(GLFWwindow* handle)
  {
      _GLFWwindow* window = (_GLFWwindow*) handle;
      _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
  
      if (_glfw.platform.platformID != GLFW_PLATFORM_WIN32)
      {
          _glfwInputError(GLFW_PLATFORM_UNAVAILABLE,
                          "WGL: Platform not initialized");
          return NULL;
      }
  
      if (window->context.source != GLFW_NATIVE_CONTEXT_API)
      {
          _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
          return NULL;
      }
  
      return window->context.wgl.handle;
  }
  
  